The invention relates to a method of recording information on a record carrier having a recording layer in which an optically detectable change can be realized by heating the recording layer. In accordance with the recording layer is scanned by means of a radiation beam whose power is modulated in a pulse pattern related to the information to be recorded, the pulse pattern having radiation pulse which have high power alternating with intervals which have a low power level, the power within each radiation pulse decreasing in order to compensate for the temperature rise caused by the power applied to the recording layer during the previous part of that radiation pulse.
The invention also relates to a device for recording information on a record carrier having a recording layer in which an optically detectable change can be realized by heating the recording layer. The device comprises a radiation source for generating a radiation beam, a scanner for scanning the recording layer by means of the radiation beam, a write signal generating circuit for converting an information signal to be recorded into a write signal having a pulse pattern, the pulse pattern having pulses which have high signal levels (i.e., values) alternating with intervals which have a low signal level (i.e., values) the signal levels (i.e., values) within each pulse decreasing, and a control circuit for setting the instantaneous value of the power of the radiation beam at each instant to a value which is fixed by the instantaneous signal level (i.e., value) of the write signal.
A method and device of the type described in the opening paragraphs are known from U.S. Pat. No. 4,894,816. In the known method and device, the recording layer is scanned by means of a radiation beam in the form of a laser beam whose power is modulated in a pulsatory manner. During each radiation pulse, the recording layer is heated above a write temperature above which the recording layer undergoes an optically detectable change. During the intervals, the temperature in the recording layer drops below the write temperature. Thus, an information pattern of areas having changed optical properties is obtained. The initial value of each radiation pulse is exponentially dependent on the length of the previous interval. Within the radiation pulse itself the power decreases exponentially as a function of time. Thus during the formation of areas having changed properties, the temperature in the scanned portion of the recording layer is maintained at substantially the same level, which means that the dimensions of the areas provided are well defined. The jitter in the read signal during reading of an information pattern which consists of such areas with optically detectable changes is then small, which renders a high information density on the record carrier possible. In the known method the power of the radiation pulse is constant during the intervals.